Monitoring device comprising a master machine and slave machine

ABSTRACT

The monitoring device according to the present invention is a monitoring device A which comprises a master machine  101  comprising plural cameras  102 , a camera interface circuit  103 , a master machine control unit  104 , a master machine radio transmitter  105 , a master machine antenna  106 , a recording unit  107 , master machine operation buttons  108  and a power circuit  109 , and a slave machine  110  comprising a slave machine antenna  111 , a slave machine radio transmitter  112 , a monitor unit  113 , a monitor interface circuit  114 , a slave machine control unit  115 , slave machine operation buttons  116 , a lamp  117 , a buzzer  118 , a vibrator  119  and a battery  120 , as shown in FIG.  1.

TECHNICAL FIELD

The present invention relates to a monitoring device and, moreparticularly, to the monitoring in a small-scale store or the like whichis managed by a few staffs.

BACKGROUND ART

A conventional monitoring device 301 has a structure as shown in FIG. 3.As shown in FIG. 3, this conventional monitoring device 301 has pluralcameras 302 (four cameras in FIG. 3), a camera interface circuit 303, acontrol unit 304, a recording unit 305, operation buttons 306, a powercircuit 307, a monitor interface circuit 308, a monitor unit 309, and anemergency button/door contact 310.

The operation of this monitoring device 301 is briefly described withreference to FIG. 3.

Initially, the operation buttons 306 of the monitoring device 301 areoperated to set the recording mode of the monitoring device 301. As therecording mode, there are a “normal mode” in which images taken by thecameras 302 are recorded at one of frame advance speeds: (one frame inseveral seconds), (one frame in several minutes) and (frame advance at alower speed), and an “emergency model” in which images taken by thecameras 302 are recorded at a higher frame advance speed than that ofthe “normal mode”. The frame advance speed at which the images taken bythe cameras 302 are recorded is set for each of the modes.

In addition, it is possible to previously set the selection of images,i.e., which images are to be recorded among the images taken by theplural cameras 302. For example, the setting that the recording issuccessively switched in the following order: images taken by the camera302 a, images taken by the camera 302 b, images taken by the camera 302c and images taken by the camera 302 d at predetermined periods ispossible.

When the setting of the recording mode is terminated, the monitoringoperation is started in the normal mode. The monitoring device 301records the images taken by a previously selected camera 302 in therecording unit 305, in accordance with the previously set recordingmode. While these images are recorded, an image which is being taken bythe camera 302 is displayed on the monitor unit 309 to show the imagewhich is being taken by the camera 302 to a user.

At this time, when the user perceives the emergency and pushes theemergency button 310, the monitoring device 301 switches the mode intothe previously set emergency mode, and records the images which aretaken by the previously selected camera 302 in the recording unit 305.

When the “emergency mode” is set so that the images are always recordedwithout the emergency button 310 being pushed and the images which havebeen already recorded are retained without being overwritten when theemergency button 310 is pushed, the images before the emergency button310 is pushed also can be recorded.

As described above, the conventional monitoring device 301 is used forthe image recording in accordance with the recording mode. Besides, in asmall-scale store such as a convenience store, the monitoring device 301can shoot places behind the shelves of goods, which are not seen by acashier, using the cameras 302. Then, the images taken by the cameras302 are displayed on the monitor 309, whereby whether these are manycustomers or not can be grasped. Further, when the monitor 309 isinstalled in a place which can be seen by the customers to inform thecustomers that the store is being shot by the monitoring cameras, themonitoring device is used to prevent wrongful acts such as shoplifting.

However, when the above-mentioned monitoring device 301 is used in thesmall-scale store, such as a convenience store, which is managed by afew staffs, the monitor 309 is normally installed near the register.Therefore, for example when the staff has to leave the vicinity of theregister to go for the goods to be supplied to the storage or to arrangethe goods in the shelves, i.e., while the staff is doing these works,the staff cannot grasp whether or not there are many customers in thestore or monitor the store.

In addition, when the monitoring device is used in the above-mentionedway, the clerk can grasp movements of the customers by seeing themonitor 309 when the clerk is near the register. Thus, when a customerapproaches the register to make the payment for example, the clerk canserve the customer immediately. However, when the customer approachesthe register to make the payment when the clerk is away from theregister, the clerk cannot serve the customer immediately. The prior arthas problems in serving the customers.

Further, when an illegal act such as robbery and shoplifting occurs whenthe staff is away from the register, since the emergency button providedin the monitoring device 301 is also placed near the register in manycases, the staff cannot push the emergency button immediately even ifhe/she finds this illegal act. Consequently, the monitoring device failsto take the images in the emergency, which may evidence the illegal act.

The present invention is made to solve the above-mentioned problems. Itis an object of the present invention to provide a monitoring devicewhich enables to always easily grasp the circumstances in a small-scalestore, such as a convenience store having a few clerks, wherever theclerks are.

DISCLOSURE OF THE INVENTION

A monitoring device according to the present invention (claim 1)comprises one master machine and at least one slave machine, and in themonitoring device, the master machine comprises at least: pluralcameras; video signal output means for outputting images taken by theplural cameras as video signals; entrance detection means for detectingan entrance of a mobile body and outputting a mobile body detectionsignal, when the mobile body enters one of shooting ranges of the pluralcameras; mobile body image selection means for automatically selectingimages taken by one of the cameras, which camera has shot the mobilebody, in accordance with input of the mobile body detection signal;master machine radio transmission means for transmitting the videosignals and the mobile body detection signal to the slave machine aswell as receiving a signal transmitted from the slave machine; andshooting camera switching means for selecting the images taken by thecamera in accordance with the signal transmitted from the slave machine,and the slave machine comprises at least: image selection means forselecting one of the video signals of the images taken by the pluralcameras; image selection signal generation means for outputting an imageselection signal to the master machine when the image selection meansare operated; a monitor unit for displaying the video signal selected bythe image selection means; at least one warning unit for issuing awarning in accordance with the mobile body detection signal; actuationmeans for actuating the warning unit when the mobile body detectionsignal is received; and slave machine radio transmission means fortransmitting the image selection signal as well as receiving the signalstransmitted from the master machine.

According to the so-constructed monitoring device, the radio contact canbe established between the slave machine having the monitor unit and themaster machine, in a small-scale store, such as a convenience storewhich is managed by a few clerks. Therefore, even when the clerk carriesthe slave machine, the information from the master machine can betransmitted to the slave machine. Accordingly, even when the clerk goesfor the goods to be supplied or arranges the goods in the shelves, theclerk can monitor the store to grasp the number of customers in thestore. Besides, even when the clerk is absorbed in the supply orarrangement of goods and looks asides the slave machine, the warningunits inform that a customer in the store comes to the register withgoods, after the mobile body is detected. Further, the staff can checkthis situation using the image on the monitor of the slave machine.Therefore, the quick services can be given to the customers.

According to the present invention (claim 2), in the monitoring deviceof claim 1, the slave machine comprises fixing means for fixing theslave machine.

According to the so-constructed monitoring device, the slave machine canbe for example easily hanged on a part of the uniform of the clerk orput on a wall near the place where the clerk is. Therefore, the slavemachine can be carried more easily, whereby the monitoring devicebecomes suitable.

According to the present invention (claim 3), in the monitoring deviceof claim 2, the fixing means is a hook.

According to the so-constructed monitoring device, the slave machine canfor example be hanged on a part of the uniform of the clerk. Therefore,the slave machine can be carried more easily, whereby the monitoringdevice becomes suitable.

According to the present invention (claim 4), in the monitoring deviceof claim 2, the fixing means is a magnet.

According to the so-constructed monitoring device, the slave machine canfor example be easily put on the wall near the place where the clerk is.Therefore, the slave machine can be carried more easily, whereby themonitoring device becomes suitable.

According to the present invention (claim 5), in the monitoring deviceof one of claims 1 to 4, the warning unit is a lamp.

According to the so-constructed monitoring device, even when the userlooks aside the monitor, the user can know the warning immediately bythe flashing light.

According to the present invention (claim 6), in the monitoring deviceof one of claims 1 to 4, the warning unit is a buzzer.

According to the so-constructed monitoring device, even when the user isslightly away from the slave machine, the user can know the warningimmediately by the sound.

According to the present invention (claim 7), in the monitoring deviceof one of claims 1 to 4, the warning unit is a vibrator.

According to the so-constructed monitoring device, the user can know thewarning without being noticed by those around the user, such ascustomers.

According to the present invention (claim 8), in the monitoring deviceof one of claims 1 to 4, the warning unit is at least one of a lamp, abuzzer and a vibrator.

According to the so-constructed monitoring device, even when the user isaway from the slave machine, the warning can be informed to the user.Further, when the two or more warning units are combined, the warningcan be informed more surely.

According to the present invention (claim 9), in the monitoring deviceof one of claims 1 to 8 comprises: the mobile body detection signals asmany as the plural cameras, said mobile body detection signals havingcontents which differ; and the actuation means corresponding to each ofthe mobile body detection signals having the contents which differ.

According to the so-constructed monitoring device, the camera which hasdetected the mobile body can be known immediately. Therefore, the clerkcan cope with the mobile body quickly, whereby the monitoring devicebecomes more suitable.

According to the present invention (claim 10), in the monitoring deviceof one of claims 1 to 9, the slave machine comprises emergency recordingoperation means for recording circumstances in an emergency; andemergency recording signal generation means for generating an emergencyrecording signal when the emergency recording operation means areoperated, and the emergency recording operation means starts recordingthe images taken by the plural cameras when the master machine receivesthe emergency recording signal.

According to the so-constructed monitoring device, the user can switchthe images to the images to be selected with checking the monitor imagestaken by the plural monitoring cameras using the slave machine at hand.Further, when the staff perceives the emergency-from the monitor imagesof the slave machine, the staff can promptly pushes the emergencybuttons. Therefore, the good monitoring device which is efficient andsufficient even when the staff is away from the register and does notfail to take images in the emergencies can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a monitoring device according toan embodiment of the present invention.

FIG. 2 are external views illustrating a slave machine according to theembodiment of the present invention.

FIG. 3 is a block diagram illustrating a prior art monitoring device.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings. The embodiment described herein is shownas an example and the present invention is not limited to thisembodiment.

Embodiment 1

Initially, a monitoring device A according to the present invention isdescribed as a first embodiment with reference to the drawings.

This monitoring device A comprises one master machine 101 and one slavemachine 110. However, the number of the slave machine 110 is not alwayslimited to one. For example, the monitoring device A may comprise onemaster machine 101 and plural slave machines 110. However, in thefollowing description, assume that one slave machine 110 is provided.

FIG. 1 is a block diagram illustrating a structure of the monitoringdevice A comprising one master machine 101 and one slave machine 110.FIG. 2 are external views illustrating the slave machine 110.

Elements of the monitoring device A are described with reference to FIG.1.

As shown in FIG. 1, the monitoring device A comprises the master machine101 and the slave machine 110.

The master machine 101 comprises plural cameras 102 a, 102 b, 102 c and102 d, a camera interface circuit 103, a master machine control unit104, a master machine radio transmitter 105, a master machine antenna106, a recording unit 107, master machine operation buttons 108, and apower circuit 109.

The slave machine 110 comprises a slave machine antenna 111, a slavemachine radio transmitter 112, a monitor unit 113, a monitor interfacecircuit 114, a slave machine control unit 115, slave machine operationbuttons 116, a lamp 117, a buzzer 118, a vibrator 119, and a battery120.

Next, the operations of the respective elements are described.

The cameras 102 attached to the master machine 101 take images of arounda place where the master machine 101 is installed, and transmit takenimages as video signals to the camera interface circuit 103. While thefour cameras are available in this embodiment, the number of the camerasis not always limited to four. Plural cameras, for example three or fivecameras, are required.

The camera interface circuit 103 operates as a video signal output meansfor outputting the video signals which are transmitted by the fourcameras 102, to the master machine control unit 104.

The master machine control unit 104 has a function of a shooting cameraswitching means for selecting one video signal from four types of thevideo signals which are input by the four cameras 102 through the camerainterface circuit 103, and outputting the selected signal to the mastermachine radio transmitter 105. This selection of the video signal isperformed in accordance with an image selection signal which istransmitted by the slave machine 110, which is described later.

The master machine control unit 104 operates also as a mobile bodyentrance detection means for detecting that a mobile body enters one ofshooting areas of the four cameras 102 as well as outputting a mobilebody detection signal informing that the entrance of the mobile body isdetected. Further, the master machine control unit 104 has a function ofoutputting the mobile body detection signal to the master machine radiotransmitter 105, when the entrance of the mobile body is detected.Further, the control unit 104 also has a function of a mobile body imageselection means for detecting a camera 102 among the four cameras 102,having the shooting range in which the mobile body enters, andautomatically selecting the images of the camera 102 which takes theimage of the mobile body.

The master machine radio transmitter 105 transmits the video signals andmobile body detection signal which are input by the master machinecontrol unit 104, from the master machine antenna 106 toward the slavemachine 110.

The master machine operation buttons 108 set the recording mode of themonitoring device A. This recording mode is the same as that in theaforesaid conventional monitoring device 301. While the setting of therecording mode is performed using the master machine operation buttons108 here, this operation does not always require the buttons. The imagestaken by the cameras 102 are recorded in the recording unit 107, inaccordance with the recording mode which is set by the master machineoperation buttons 108.

The recording unit 107 records all or part of the images taken by thecameras 102, in accordance with the recording mode which is set by themaster machine operation buttons 108. For example, these images can berecorded on videotapes. However, the recording method is not limited tothis method. When the videotapes are endless videotapes, the latestimage can always be recorded. In addition, the images to be recordedtaken by a camera 102 are selected among the four cameras 102 inaccordance with the image selection signal transmitted by the slavemachine 110, which is described later.

The slave machine radio transmitter 112 receives the video signal andmobile body detection signal which are transmitted by the master machine101 via the slave machine antenna 111, and outputs these signals to theslave machine control unit 115. In addition, the transmitter 112transmits the image selection signal which is described later to themaster-machine 101.

The slave machine control unit 115 outputs the video signal transmittedby the master machine 101 to the monitor interface circuit 114. Then,the monitor interface circuit 114 converts this video signal into animage, and displays the image on the monitor 113.

In addition, the slave machine control unit 115 has an actuation meanswhich actuates the lamp 117, the buzzer 118 and the vibrator 119 whenthe mobile body detection signal transmitted by the master machine 101is input thereto.

In this embodiment, the lamp 117, the buzzer 118 and the vibrator 119are provided as warning units. However, units other than these units canbe employed. Further, only one or two of these units can be provided. Inthe following description, assume that the above-mentioned three unitsare provided.

The slave machine operation buttons 116 operate as image selection meanswhich select images of a place which is desired by the user, among theimages taken by the four cameras 102 of the master machine 101. When theslave machine operation buttons 116 are operated to select a desiredcamera 102, the slave machine control unit 115 generates the imageselection signal and transmits the signal to the master machine 101.

In addition, as shown in FIG. 2, a hook 130 and a magnet 131 as fixingmeans are provided at the back of the slave machine 110. These means arenot always required to be at the back of the slave machine 110. Further,it is possible to provide only one of these means. It does not matterthat the slave machine 110 has no fixing means, but the fixing means areprovided in this embodiment for reasons which are described later.

Hereinafter, the operation of the so-constructed monitoring device Aaccording to this embodiment will be described. In the followingdescription, assume that the monitoring device A is used in aconvenience store.

Initially, the master machine 101 is installed in an appropriate placein the store. Here, it is important that the master machine 101 isinstalled in a place where the cameras 102 of the master machine canshoot whole places in the convenience store.

Next, the slave machine 110 is installed in a place where the clerk canalways see the monitor 113. Since the slave machine 110 comprises thefixing means, i.e., the hook 130 and the magnet 131, when the clerk isat the register, the slave machine 110 can be provided near the registerusing the magnet 131. When the clerk leaves the register, the clerk cancarry the slave machine 110 using the hook 130, whereby the clerk alwaysknows how it is in the store wherever the clerk is.

When the monitoring device A is installed in this way, the operationbuttons 108 of the master machine 101 are then operated to set therecording mode. The description of the recording mode is already given.When the recording mode is set, the cameras 102 start taking images inaccordance with the set mode. All or part of the images taken by thecameras are recorded in the recording unit 107.

The images taken by the cameras 102 of the master machine 101 are outputby the camera interface circuit 103 as video signals to the mastermachine control unit 104. The video signals are transmitted to the slavemachine 110 through the master machine radio transmitter 105.

The video signals received by the slave machine 110, which signals areobtained from the images taken by the cameras 102, are input to theslave machine radio transmitter 112 and sent to the slave machinecontrol unit 115. Then, the signals are sent to the monitor 113 throughthe monitor interface circuit 114. Then, the images taken by the cameras102 are displayed on the monitor 113.

While the cameras 102 of the master machine 101 are taking images, whena mobile body enters in the shooting range of one of the cameras 102,i.e., the camera 102 a in this case, the master machine control unit 104receives the image of the mobile body and detects that the mobile bodyhas entered. Then, the unit 104 automatically selects the image taken bythe camera 102 a and outputs the image to the slave machine 110. At thesame time, the master machine control unit 104 outputs and transmits amobile body detection signal to the slave machine 110 to inform that theentrance of the mobile body is detected.

Then, the slave machine 110 receives the video signal of the camera 102a which is automatically selected by the master machine control unit104, and displays the image on the monitor 113. At the same time, theslave machine control unit 115 receives the mobile body detection signaloutput by the master machine control unit 104, and actuates the warningunits. To be specific, the slave machine control unit 115 controls thelamp 117 to blink, the buzzer 118 to sound, or the vibrator 110 tovibrate.

Since the slave machine 110 is always near the clerk as mentioned above,the staff knows immediately that a customer comes to the register andcan serve the customer quickly, even when the clerk is away from theregister.

In this case, the clerk can always see the image of a desired one of thecameras 102 by operating the slave machine operation buttons 116.

As described above, the monitoring device A according to this embodimentcan easily monitor a store even when this is managed by a few staffs,thereby being suitable. In addition, when the mobile body enters theshooting ranges of the cameras 102, the warning units are actuated.Therefore, even if the clerk looks aside the monitor 113, the clerkimmediately knows the entrance of the mobile body, whereby themonitoring device is preferable.

In addition, the above-mentioned monitoring device A is constructed sothat the warning units are actuated when the mobile body enters theshooting range of one of the four cameras 102. However, for example whenthe ways of actuating the warning units vary with the four cameras 102,it can be easily seen which one of the cameras 102 has a shooting rangewhere the mobile body enters.

If these measures are not taken, even when the mobile body is to bechecked after the actuation of the warning units is checked, it can notbe seen which one of the cameras 102 detects the mobile body. Therefore,the cameras 102 should be switched successively, thereby requiring timeand effort. However, when these measures are taken, the mobile body canbe quickly checked.

For example, the shooting ranges of the cameras 102 a˜102 d arepreviously decided. For example, the camera 102 a is set to take imagesof the register, the camera 102 b is set to take images of the entrance,the camera 102 c is set to take images of half of the selling area, andthe camera 102 d is set to take images of the other half of the sellingarea.

When the mobile body enters in the shooting range of one of the cameras102, taking the camera 102 a in this case, the mobile body detectionsignal is output by the master machine control unit 104 as mentionedabove. The content of the signal is previously decided so as to varywith cameras. That is, the master machine control unit 104 is previouslyset to output a mobile body signal 1 when the camera 102 a detects theentrance of the mobile body, a mobile body signal 2 when the camera 102b detects the entrance of the mobile body, a mobile body signal 3 whenthe camera 102 c detects the entrance of the mobile body, and a mobilebody signal 4 when the camera 102 d detects the entrance of the mobilebody.

At the same time, in the slave machine control unit 115, the ways ofactuating the warning units, for example, the blinking ways of the lamp117, the kinds of the sound of the buzzer 118, and the vibration ways ofthe vibrator 119 are previously set so as to vary with the kind of thereceived mobile body signal.

In this case, for example if the camera 102 a detects the mobile body,the area where the mobile body is detected is easily known on the slavemachine 110 side only by the actuation ways of the warning units.Therefore, at the same time when the warning units are actuated,switching to a desired one of the cameras 102 can be immediatelyperformed, i.e., the clerk can quickly cope with the situations. To bespecific, even when the clerk looks aside the slave machine, the clerkcan easily detect that, for example, a customer as the mobile bodyapproaches the vicinity of the register, according to the actuationtypes of the warning units. Further, when the clerk sees the monitor ofthe slave machine, displaying the images taken by the camera whichdetected the mobile body, the clerk can judge whether the customer comesto the register after finishing picking up goods or only passes near theregister. Therefore, the clerk knows that the customer comes to theregister after finishing the picking up the goods promptly. Accordingly,the clerk can quickly return to the register, whereby the good servicescan be given. In this case, when the switching of the images isperformed automatically, it is more preferable.

In addition, the above-mentioned monitoring device A can include a meansfor recording situations in emergencies in detail when the emergenciessuch as a case where the robbers enters the store occur.

This monitoring device A includes a function of an emergency recordingoperation means in the slave machine operation buttons 116. When theslave machine operation buttons 116 are operated, the slave machinecontrol unit 115 generates an emergency recording signal. When themaster machine 101 receives the emergency recording signal, the mastermachine control unit 104 automatically changes the recording mode to theemergency mode, and starts recording the mobile body taken by the camera102 in the recording unit 107 in the emergency mode.

To be more specific, the mobile body detected by the camera 102 isautomatically displayed on the monitor 113 of the slave machine 110 asmentioned above. Then, when the user, i.e., the clerk of the conveniencestore in this case, detects that the mobile body displayed on themonitor 113 is a robber, the clerk operates the slave machine operationbuttons 116 to transmit the emergency recording signal from the slavemachine 110 to the master machine 101. When an emergency recordingbutton is provided separately from the slave machine operation buttons116, erroneous operations can be prevented, whereby it is morepreferable.

When the master machine 101 receives the emergency recording signal, theimages taken by the camera 102, which have been recorded in the normalmode until then, are recorded by the recording unit 107 in accordancewith the emergency mode in which the images are recorded at higher frameadvance speed than that of the normal mode.

That is, when the images are recorded at the higher frame advance speed,the motions of the mobile body, i.e., the robber in this case, arerecorded in more detail, thereby being expected to be more helpful indealing with it later.

When the monitoring device A is constructed so as to cope with theemergencies, whether or not the emergency recording is to be performedcan be selected after the slave machine operation buttons 116 areoperated to check the images taken by the four cameras 102. Besides,when the emergency recording is required, the slave machine operationbuttons 116 are operated to control the emergency recording from a placeapart from the master machine 101. Therefore, the recording can beimmediately performed in the emergencies, whereby it is more suitable.

In this embodiment, the operation times of the lamp, the buzzer and thevibrator are varied with the respective cameras when the mobile bodydetection signal is received. However, it is also useful that the lamp,the buzzer and the vibrator are operated intermittently and the timeintervals are varied, or have different rhythm or different melody foreach camera. Further, it is also useful that the lamp, the buzzer andthe vibrator are operated only when the mobile body is detected by thecamera near the register and are not operated when the mobile body isdetected by other cameras.

INDUSTRIAL AVAILABILITY

As described above, the monitoring device according to the presentinvention can detect mobile bodies using the warning units even when theuser looks aside the monitor. In addition, the slave machine of themonitoring device has portability. Therefore, the user can carry theslave machine, thereby the mobile bodies can be detected even when theuser is away from a place where the master machine of the monitoringdevice is installed. Accordingly, the monitoring device is particularlysuitable for a use in a small-scale store such as a convenience store.When the clerk carries the slave machine, the clerk can grasp movementsof customers in the store using the information transmitted by themaster machine. For example, even when a customer in the store comes tothe register with goods while the clerk arranges goods in shelves, theclerk knows the movement of the customer in front of the register usingthe warning units.

What is claimed is:
 1. A monitoring device comprising one master machineand at least one slave machine, wherein the master machine comprises atleast: plural cameras; video signal output means for outputting imagestaken by the plural cameras as video signals; entrance detection meansfor detecting an entrance of a mobile body and outputting a mobile bodydetection signal, when the mobile body enters one of shooting ranges ofthe plural cameras; mobile body image selection means for automaticallyselecting images taken by one of the cameras, which camera has shot themobile body, in accordance with input of the mobile body detectionsignal; master machine radio transmission means for transmitting thevideo signals and the mobile body detection signal to the slave machineas well as receiving a signal transmitted from the slave machine; andshooting camera switching means for selecting the images taken by thecamera in accordance with the signal transmitted from the slave machine,and the slave machine comprises at least: image selection means forselecting one of the video signals of the images taken by the pluralcameras; image selection signal generation means for outputting an imageselection signal to the master machine when the image selection meansare operated; a monitor unit for displaying the video signal selected bythe image selection means; at least one warning unit for issuing awarning in accordance with the mobile body detection signal; actuationmeans for actuating the warning unit when the mobile body detectionsignal is received; and slave machine radio transmission means fortransmitting the image selection signal as well as receiving the signalstransmitted from the master machine.
 2. The monitoring device of claim 1wherein the slave machine comprises fixing means for fixing the slavemachine.
 3. The monitoring device of claim 2 wherein the fixing means isa hook.
 4. The monitoring device of claim 3 wherein the warning unit isa lamp.
 5. The monitoring device of claim 3 wherein the warning unit isa buzzer.
 6. The monitoring device of claim 3 wherein the warning unitis a vibrator.
 7. The monitoring device of claim 3 wherein the warningunit is at least one of a lamp, a buzzer and a vibrator.
 8. Themonitoring device of claim 2 wherein the fixing means is a magnet. 9.The monitoring device of claim 8 wherein the warning unit is a lamp. 10.The monitoring device of claim 8 wherein the warning unit is a buzzer.11. The monitoring device of claim 8 wherein the warning unit is avibrator.
 12. The monitoring device of claim 8 wherein the warning unitis at least one of a lamp, a buzzer and a vibrator.
 13. The monitoringdevice of claim 2 wherein the warning unit is a lamp.
 14. The monitoringdevice of claim 2 wherein the warning unit is a buzzer.
 15. Themonitoring device of claim 2 wherein the warning unit is a vibrator. 16.The monitoring device of claim 2 wherein the warning unit is at leastone of a lamp, a buzzer and a vibrator.
 17. The monitoring device ofclaim 1 wherein the warning unit is a lamp.
 18. The monitoring device ofclaim 1 wherein the warning unit is a buzzer.
 19. The monitoring deviceof claim 1 wherein the warning unit is a vibrator.
 20. The monitoringdevice of claim 1 wherein the warning unit is at least one of a lamp, abuzzer and a vibrator.
 21. The monitoring device of claim 1 comprising:the mobile body detection signals as many as the plural cameras, saidmobile body detection signals having contents which differ; and theactuation means corresponding to each of the mobile body detectionsignals having the contents which differ.
 22. The monitoring device ofclaim 1 wherein the slave machine comprises emergency recordingoperation means for recording circumstances in an emergency; andemergency recording signal generation means for generating an emergencyrecording signal when the emergency recording operation means areoperated, and the emergency recording operation means starts recordingthe image taken by the plural cameras when the master machine receivesthe emergency recording signal.